1. Field of the Invention
The present invention generally relates to glazing panels and to such panels utilized in automotive applications. More particularly, the present invention relates to the transferring of an image onto a glazing panel having a raised portion about the perimeter of the glazing panel and adjacent thereto.
2. Description of Known Technology
Plastic materials are being used in a number of automotive engineering applications to enhance vehicle styling. For example, polycarbonate is currently used in the manufacturing of B-pillar covers, headlamps, and sunroofs. An emerging application for transparent plastic materials is automotive glazing panel applications, such as windows and panoramic roof systems. When plastics are used to manufacture automotive windows and panoramic roof systems, it is a manufacturing requirement that such windows maintain a certain degree of rigidity. The perimeter of a window often must be reinforced or supported in order to enhance the rigidity of the installed window or roof system. Additionally, it is also a manufacturing requirement that plastic windows and panoramic roof systems are coated to make them scratch resistant.
One method of reinforcing the perimeter of a plastic window or roof system is to injection mold the window in a two shot process. This particular type of injection molding is known as two-component molding. More specifically, the transparent portion of the plastic panel is typically formed in the introduction of a transparent resin (1st shot) into a mold. A second shot is subsequently introduced into a mold, usually around the perimeter of the plastic panel formed by the first shot. This second shot can be formed so as to integrate various types of functionality into the plastic panel, such as ribs, placement fixtures, etc. This second shot, which can be of the same or different resin, transparent or opaque, and of the same or different stiffness, must adhere to the plastic panel made by the first shot through melt bonding with the plastic panel. U.S. Pat. No. 6,764,638 discloses a two shot method and is herein incorporated by reference. This second shot, however, produces a raised frame portion around the perimeter of the transparent panel.
Issues that must be addressed if two component molding is used to produce glazing panels, plastic windows, roof systems or similar systems (herein just referred to as “plastic windows”) is the ability to effectively apply any border image, decoration or logo information to the transparent portion of the molded plastic panel. Sometimes, such border images are used to hide or mask aesthetic defects or mounting structures of the window assembly. One form of an aesthetic defect is the formation of a distortion line on the plastic panel. This distortion line typically runs parallel to the edge that the second shot makes with the first shot. This aesthetic defect is described as “picture framing” or “window effect”, depending upon the root cause of the defect. The root cause of the “picture framing” is the application of a protective coating, while the “window effect” arises from the molding process itself.
A known problem with printing on plastic panels is that such panels often have complex shapes (concave, convex, compound curvature, etc.) as a direct result of the molding capabilities of the plastic. Screen printing is a known commercial process but is limited by the complexity of the shape of the surface to be printed upon. To utilize screen printing for surfaces other than “flat” substrates, various modified processes must be employed. One such process is a technique known as in mold decoration (IMD). In this technique the printed image is applied via screen printing to a “flat” film. The film is then held either by a vacuum to the surface contour of the mold or is itself formed so as to conform to the surface of the mold. Upon injection of the plastic material into the mold, the film becomes part of the surface of the molded article. Another printing technique is known as membrane image transfer (MIT) printing. A membrane is located in a print station where an image is printed onto the membrane by screen printing or a similar process. The printed membrane is then moved to a transfer station. In the transfer station a substrate fixture holds the substrate and a forming fixture shapes the membrane and moves the membrane into contact with the substrate. Pressure is applied to this fixture combination to effect a transferring of the image from the membrane to the substrate. Once the image is transferred to the substrate, the pressure is released. U.S. Pat. No. 6,776,100 and U.S. Pat. No. 6,964,226 each disclose various aspects of MIT printing and are herein incorporated by reference.
While IMD and MIT printing can be used to transfer an image to a complex shape, these processes are limited in their ability to transfer the image to an area adjacent and precisely aligned with a step height change along the surface of the window assembly. The above mentioned processes are limited by their inability to have the membrane conform to the step height change along the surface of the window assembly.
As seen from the above, there is a need for a system, method and article that overcomes the limitations and drawbacks of the known technology.